This invention relates generally to a harvesting apparatus and more specifically to a self-propelled harvester especially suited for harvesting small leafy vegetables including but not limited to baby spinach and lettuce type greens.
A wide variety of lettuce-type greens including baby leaf spinach, tango, lolla roas, red oak leaf, baby romaine, green oak leaf, baby red romaine, baby red chard, red mustard, Totsoi, Mizuma, Frisee, arruagula, radicchio, and curly endives are currently grown, and are typically referred to in the trade under the term xe2x80x9cbaby greens.xe2x80x9d They are harvested well before maturity for freshness and tenderness. Baby greens are typically used for mixed or one of a kind salads and garnishes in restaurants and in pre-packaged bags available at grocery stores. Shelf life is critical to the greens market. It takes a significant amount of time after harvest for the greens to pass through processing and distribution to market. Greens crush and bruise easily, and subsequently wilt and discolor to brown within a matter of hours. Wilted and bruised greens leaves are undesireable. Therefore, great care must be taken in handling the greens through the entire process of harvesting and moving the product from the field to the market. To minimize damage during harvesting, greens must be severed without pulling, tearing or shredding, and must be handled gently as they are transported from the field.
Currently, growers are using both manual harvesting and machine harvesting of baby greens. Each of the prior harvesting means has disadvantages. Manual harvesting of baby greens requires many farm laborers to enter the fields and kneel or lean across the bed to sever the stems of the baby greens adjacent to the earth with a knife or sickle. The laborer then places the severed greens by hand into carrying boxes called totes, which are stacked in pallets for transportation. Manual harvesting has a number of significant disadvantages. Firstly, the cost of the numerous laborers is high. Second, the low height of the baby greens means that when the top is gripped by the worker, the worker must cut fairly close to his or her hand, and as a result, many workers are injured in the fields. Third, hand harvesting necessarily limits the width of the beds to 36 to 48 inches between furrows, which is a width reachable by the workers. Narrower furrows have the adverse effect of reducing the yield per acre of product from the yield that could be obtained with wider furrows. Fourth, the harvest period for hand harvesting is typically from 6:00 am to 10:00 am in the morning, before which it may be too dark for the workers to work safely, and after which the whether may be too hot as the cut greens will wilt too fast. Thus in a typical 3-4 hour cutting day, a working can produce only about 15 totes. Lastly, it is not possible to get an accurate and uniform even cut at a specified height when harvesting by hand.
A number of self-propelled harvesters have been developed to harvest baby greens. These harvesters overcome some of the problems encountered in harvesting by hand, however, a number of other problems have been encountered. For example, Prior art harvesters have been complicated and expensive to purchase and maintain. Some prior art harvesters are extremely heavy vehicles. Furthermore, the high weight of such harvesters can disrupt the structure of the furrows, possibly requiring that the field be replowed after each harvest. The high weight and size of these harvesters can make the prior harvesters difficult to transport from field to field. Lastly, the cutting and collecting methods used by prior harvesters frequently results in damage to the delicate baby greens.
Whether the baby greens are harvested by hand or by machine, it is preferred that the harvested baby greens consist mostly of whole leaves, and that smaller pieces and cotyledon leaves be discarded. Sorting baby greens is difficult after the leaves have been harvested and placed in totes or other storage containers because the leaves tend to clump together.
What is needed is a harvester that is lightweight, inexpensive to maintain, and that will harvest the greens in a manner optimal to retaining freshness and shelf life, and that can sort the cut greens in the field to remove unwanted material before the product becomes bunched in storage containers.
Accordingly, the present invention is a harvester that is particularly suited for harvesting baby greens. The harvester includes a chassis and a floating header that can move independently of the chassis to follow the contours of the top of a raised bed. The floating header includes a header frame supporting a cutting assembly, and a ground contact assembly that runs on the top surface of the raised bed and supports the weight of the floating header. In the preferred embodiment the cutting assembly comprises a band saw with a band saw blade having a knife edge rather than toothed edge. An articulated coupling assembly couples the chassis and the floating header to allow the floating header to move vertically relative to the chassis, and to rotate perpendicular to a front to back axis of the chassis, or roughly perpendicular to the plane of the surface of the top of the raised bed.
One advantage of the invention is that it can sort the cut baby greens at the easiest and most effective time to do so, immediately after the baby greens are cut and before the baby greens are clumped in storage bins or other storage means. The invention includes at least one sorting belt, and preferably two sorting belts, with apertures of a selected size to accept the cut greens from the cutting assembly. The cutting assembly preferably provides a relatively even flow, at a relatively constant rate, of a single layer of leaves to the sorting assembly. In a preferred embodiment, a collection belt catches the greens cut by the cutting assembly and transfers the greens to the first sorting belt, and the second sorting belt accepts the cut greens from the first sorting belt. The first sorting belt travels at a rate approximately twice the speed of the collection belt, and the second sorting belt travels at approximately 1.5 times the speed of the collection belt. The sorting belt frame is pivotally coupled to the chassis of the harvester so that the forward end of the sorting frame can pivot up and down relative to the chassis, and also somewhat forward and back relative to the chassis, in order to follow the floating header.
In one embodiment, the articulated coupling includes four linking arms extending between a superstructure of the chassis and the header frame. The articulated coupling further includes an additional linking arm coupled to the forward end of the sorting belt frame between the header frame and the sorting belt frame. In one embodiment, the ground contact assembly includes a single ground contact roller. In an another embodiment, the ground contact assembly comprises a plurality of ground contact rollers. In yet another embodiment, the ground contact assembly comprises a belt assembly including at least one ground contact belt around at least two rollers. In a preferred embodiment, the harvester further includes a suspension system for reducing the ground pressure applied by the ground contact assembly. A preferred embodiment of the suspension system comprises at least one lift arm pivotally coupled at a first end to the chassis, and at least one spring element coupled between the lift arm and the header frame. Thus, when the lift arm pivots up, the tension on the spring increases, thereby reducing the weight applied to the surface of the raised bed by the ground contact assembly.
The invention also comprehends a method of harvesting leafy green vegetables such as baby greens, the method steps comprising: (a) providing a field planted with a selected crop density, (b) providing a harvester suitable for harvesting leafy green vegetables (c) using the forward momentum of harvester and crop density to assist the cut greens to be collected in the collection means. The method may further include the step: (d) using sorting belts on the harvester to sort the cut greens immediately after the greens are cut while the greens are transported to the storage containers.